One-step method of direct growth spherical carbon on nickel foam as high-performance binder-free electrodes for supercapacitors

Three-dimensional spherical carbon/nickel foam composites for use as non-adhesive supercapacitor electrodes were prepared using high temperature and high pressure hydrothermal methods and their energy storage capacity was assessed. The obtained electrodes exhibited an excellent capacitive behavior in KOH solutions, characterized by low contact resistance, good rate performance (82.7% retention at 10 A g−1), and high specific capacitance (296 F g−1) much higher than that of other powder carbon electrode materials (162 F g−1). Furthermore, the electrode exhibited a large energy density (41.1 Wh kg−1 at a power density of 500 W kg−1) and superior cycle stability (only 2% loss after 10,000 cycles). The developed synthesis strategy is facile and with potential application in large-scale production.